4 BULLETIN 241, U. S. DEPARTMENT OF AGRICULTURE, 
STERILIZATION OF FRUIT JUICES. 
Containers of glass, porcelain, or tinned iron (tin cans) in which 
fruit juices may be sealed and sterilized are available. The juice may 
also be poured while very hot into sterilized wooden casks which are 
then sealed. Vessels of glass possess an obvious advantage in that a 
view of the contents may be had at any time without. being opened. 
GLASS CONTAINERS. 
CARBOYS. 
The process of sterilizing the juice in glass carboys consists in fill- 
ing previously warmed 5-gallon carboys with hot juice and sealing 
them while hot. They are warmed, either by placing them for a 
time in a closet heated by steam pipes, or by partly submerging and 
rotating them in a bath of hot water. The juice is conveniently 
heated in the steam-jacketed kettle already described (page 2) and 
then poured into the hot vessel, leaving space for the stopper, which 
is forced tightly into position. 
Experience shows that the contents of partially filled carboys spoil 
more readily than those of full carboys, doubtless due to the fact that in 
the former the surface of the cork, which is further removed from the 
surface of the hot juice, does not receive the necessary heat treatment. 
When carboys of juice become infected, it is usually possible to 
trace the infection to the growth of organisms on the surface of the 
cork. It is, therefore, clear that the corks should be sterilized as 
completely as possible before use. Successful sterilization of the cork 
is somewhat difficult to accomplish. A satisfactory method consists 
in dipping the corks in melted paraffin, removing and then heating 
them in a steam closet for several days, during which time the paraffin 
is gradually absorbed. The corks should be steamed for a few 
moments or dipped in scalding water immediately before use. _ 
After cooling, the carboys should be transferred to racks in a cool 
place where they can be inspected at frequent intervals. Such ex- 
amination is imperative, as, in spite of the precautions described, a 
small portion of the juice usually shows evidence of infection, in the 
form of patches of mold floating on the surface. The flavor is often 
ereatly injured and the juice rendered worthless by such infection. 
Before the colony of mold has become larger than a small dot floating 
on the surface, it should be removed and the juice sterilized. The 
advantage of the transparency possessed by glass containers is here 
evident. If development of yeasts, with the consequent bursting of 
carboys, occurs, serious defects in technique are probable, as yeasts 
in fruit juices are very easily killed by heating. 
